Translation:I don't believe that after death we become ghosts.
Why is it становятся in this sentence with мы as the subject? I've been staring and staring and can't figure it out. I can't actually remember (it's late!) what I'd expect it to conjugate as for мы but становятся looks like third person plural. And so then I'm wondering if I've misread the subject, or if I seriously need to revise the conjugation of that verb or... insert other mistake here. I'm confused!
Yes, you're correct! "Становятся" is third person plural; there was definitely a mistake in this sentence. I fixed it now :)
I checked the conjugations on wiktionary and it seems this is a complete misspelling, in the ending anyway. It should be "мы становимся" or "мы будем становиться" for the future (if the future tense fits here)